Magnesium hydroxide suspensions containing sea-plant hydrocolloid



Durward NQEntrekin, NewBrunswick, N. J., assignor to Olin Mathieson Chemical 7 Corporation, New York, .1 ,N. Y., a corporationof Virginia,

No Drawing. Application August 15, 1956 1 Serial No.604,060

' 13 Claims; '(CL: 167-56) This invention-relates tocompositions of matter, more particularly to pharmaceutical preparations essentially ide. I "Magnesium hydroxide is widely employed as an ant; acid and/or mild laxative. For suchpurpose, magnesium hydroxide is formulated either as a magma (e. g., milk of magnesia), or as tablets. Milk of magnesia, however, is subject to various disadvantages. Thus, it tends to separate out on standing; and after freezing (and thawing), the preparation is generally unusable. Fur thermore, the viscosity and (earthy) taste of the suspension is such that it is unpalatable to children and even adults, and hence unpleasant to take.

It is an object of this invention, therefore, to provide a more stable and palatable pharmaceutical preparation escomprising-an aqueous suspension of magnesium hydroxsentially comprising an aqueous suspension of magnesium hydroxide.

This object is achieved by the compositions of this invention, which comprise an aqueous suspension of mag: nesium hydroxide in which has been incorporated a refined sea-plant hydrocolloid in an amount sufficient to stabilize the suspension without -objectionably affecting viscosity. Preferably the hydrocolloid is derived primarily from a plant of the group consisting of Chondrus crispus and Gigartina mamillosa, and essentially comprises mixed salts of a polysaccharide sulfate. Preferably too, the concentration of the hydrocolloid is at least about 0.6% by weight and below the amount objectionably affecting viscosity (readily ascertainable by test), and optimally is of the order of 0.8% by weight.

The concentration of magnesium hydroxide in the aqueous suspension may be varied considerably. Desirably, it is at least about 7% by weight; and it should, of course, be below that at which the thickness of the preparation becomes objectionable, .which is readily ascertainable by test.

The compositions of this invention may also (and desirably should) include a sweetening agent (e. g., saccharin), flavoring agent (e. g., oil peppermint), and preservatives (e. g., methyl parahydroxybenzoate, propyl parahydroxybenzoate). Some preservatives are known to be ineffective in the presence of refined sea-plant hydrocolloids, and hence should be avoided in the compositions of this invention.

The hydrocolloid employed must, of course, be soluble in cold water and of such a nature as not to precipitate or bind the magnesium. Moreover, it should desirably have an alkaline reaction, preferably providing a pH of of the order of 10. Certain refined sea-plant hydrocolloids have been found to meet these specifications exceptionally well (in addition, of course, to accomplishing the objective of improving stability and palatability). These hydrocolloids are obtained from the sea plants Chandrus crispus and Gigartina mamillosa. They are light amber to colorless, free-flowing powders (ground, for example, to pass a 40 mesh screen). They are essentially mixed salts of a polysaccharide sulfate. Galactose Such a hydrocolloid is obtained from dried Irish moss by washing to eliminate impurities, cooking to extract the hydrocolloids, separating the extract, filtering, evaporating, drying the resultant concentrate, and pulverizing-the product. Examples of hydrocolloids thus obtained are those marketed under the trade name Sea Kem by the Seaplant Chemical Corporation of New Bedford, Massachusetts. V

The composition of this invention are conveniently prepared by incorporating the hydrocolloid into the aqueous suspension of magnesium hydroxide, and homogenizing the resultant mixture. The sweetening and flavoring agents, and/or the preservative may be added at any stage. The resultant composition may then be packaged in the same manner as milk of magnesia, for use as an antacid and/or laxative in the same manner (assuming the composition has the same magnesium hydroxide concentration as milk of magnesia; it higher, the dosage would be correspondingly lowered).

The following example is illustrative of the invention:

The milk 'of magnesia is placed in a suitable stainless steel or glass-lined container equipped with a stirrer of suificient size to agitate the thick magma at a rapid rate (it may be necessary to use two stirrers to obtain sufficient agitation). The refined sea-plant hydrocolloid is added slowly, by sprinkling on the surface of the chuming liquid. After the hydrocolloid has been stirred into the milk of magnesia, the remaining ingredients are added and the stirring continued until thehydrocolloid is completely hydrated. This stirring period will take several hours, depending upon the batch size and the rate of agitation. The composition is then passed through a homogenizer of the pressure-screening type, using pressures of and 200 pounds respectively on the'first and second stages. (The preferred homogenizer is of the type which Patented May 6, 19 58 s 3 7 pumps the composition under pressure between two closely restricted surfaces, imparting a tremendous velocity to th'ecompositi'on, and causing an "abrasive action between the suspended particles and the, faces of the restricted surfaces; and such homogenizeris also arranged so as-to repeatfthe operationhin ,a second "stage; insuring a complet'elyfliomogeneoussystem.) r

'l'hefme'thyl parahydroxybenzoate ,jan'd/ or propyl para-f hydroxybenzoate "may be replaced by an equivalent p'rcservative, "or even omitted from the above formulation if desired;iandof course, the saccharin, and/ or oil of pepper-mint may' be omitted if such flavoring isnot desired, orreplaced'by other desirable flavoring agents.

'lhe'superiority of, the compositions of this invention over magnesia magma, USP, 'ihasbeen demonstrated with respect to stability, palatabi'lityand appearance (on standing, and when being dispensed), Thus, they have a ,smooth feeling as compared-to the earthyor chalky (gritin comparative laboratory tests of lithe-effect of freezing on the compositions of this invention and-milk of magnesia,iit was established that, although'freezing and subsequent-thawing caused a settling out of the suspended material in each case, the former were more easily resuspended by reshaking, andthe improved palatabilityremained substantially unimpaired.

The invention may be variously otherwise embodied within the scope of the appended claims.

1. Apharmaceutical composition comprising an aqueous suspension of magnesium hydroxide in which has been incorporated a refined sea-plant hydrocolloid, said hydrocolloid essentially comprising salts of a polysaccharide sulfate derived primarily from a plant of the group consisting of Chondrus crispus and Gigartimzmamillosa.

2. The composition of claim 1 where the concentration of the hydrocolloid is about 0.6% by weight.

3. The composition of claim 1 wherein the concentration of hydrocolloid is of the order of 0.8% by weight.

" "References{Citedin'the'file'ofthis patent ,Pharmaceutical Formulas, vol. 1, 1944, The Eliemist and Drug gists, London, England, pp. 413 and 414.

U. S. Dispensatory, 24th ed., 1947, Lippincott Co,

Philadelphia, Pa.,.pp 271, 272, 653 and 654. 

1. A PHARMACEUTICAL COMPOSITION COMPRISING AN AQUEOUS SUSPENSION OF MAGNESIUM HYDROXIDE IN WHICH HAS BEEN INCORPORATED A REFINED SEA-PLANT HYDROCOLLOID, SAID HYDROCOLLOID ESSENTIALLY COMPRISING SALTS OF A POLYSACCHARIDE SULFATE DERIVED PRIMARILY FROM A PLANT OF THE GROUP CONSISTING OF CHONDRUS CRISPUS AND GIGARTINA MAMILLOSA. 